How to change the background color of the radiobox group control to match the color of its window

What I am trying to do is have a RadioBox that has the same background color as the window it is in. The background color of the window it is in has a RGB value of 236,236,236. When I go to the RadioBox's background properties and set the RGB values to 236, the color changes to a slightly different color than what I wanted. Using the Digital Color Meter application I was able to see its color value as 230,230,230. Is there a way to make the background color of the RadioBox completely transparent so it becomes the color of its parent widget?

Thank you.